How to run a simulation with a nucleus in an isomeric state from a macro?

Dear Experts,

I was wondering if anyone could tell me how to specify that a nucleus, e.g. 121mSn, is in an isomeric state and run a simulation. Let me know if this is also possible from a macro and if there is an existing example program for that.

Thank you in advance.

Best,
Samir

Hi Samir

I think you should use GeneralParticleSource in your macro.
/gps/particle ion
/gps/ion 50 121 0 6.30 → Last number is the energy of the isomeric state
/gps/ene/mono 0 keV

Kind regards
Simon

you can do the same thing with simple ParticleGun :
/gun/particle ion
/gun/ion 50 121 0 6.31
/gun/energy 0 keV

you can also define ion directly in your PrimaryGeneratorAction.
see example basic/B3 PrimaryGeneratorAction.cc, lines ~79-86

Thank you, Simon and Michel for your suggestions.